The invention relates to a hydrogen reservoir and to a process for filling a hydrogen reservoir in which the hydrogen is absorbed and from which it can be released when desired.
It is known to store hydrogen by storing it either in gaseous form in pressure tanks at several hundred bar overpressure or in liquid form at cryogenic temperatures in special cooling tanks.
In addition, solid reservoirs are known, in which the hydrogen is absorbed, retained in the atomic structure thereof and released again when the temperature of the reservoir is increased. Since these hydrogen reservoirs require neither extreme temperatures nor high pressures, solid reservoirs are comparatively uncomplicated to handle. Such hydrogen reservoirs are therefore suitable for small-scale mobile applications, and also for use in motor vehicles. However, these storage materials can only absorb approximately 2% of their own weight in hydrogen at room temperature. This means that for example around 100 kg of the material is needed to store around 2 kg of hydrogen.
In addition, such hydrogen reservoirs require cooling during filling and heating during emptying, since hydrogen is generally released by an endothermic reaction on the part of the storage material.
Published patent application JP 60060399 discloses using hydrogen gas as a coolant for a solid reservoir of metal halides. Published patent application JP 2001208296 discloses a porous storage container which is likewise cooled using hydrogen as coolant. A hydrogen reservoir comprising a hydrogen-absorbing material is known from published patent application DE 10392240 T5, said hydrogen reservoir having a fiber-reinforced housing.
Patent DE 69714233 T2 discloses a solid hydrogen reservoir comprising an open-pore metal foam, which functions as a carrier matrix for a pulverulent, hydrogen-absorbing storage material. The pulverulent material is dispersed in the carrier matrix. To make entrainment of the finely dispersed material from the hydrogen reservoir more difficult, the carrier matrix is subdivided into segments, which are sealed off with partition walls which retain the storage material within the respective segments. Pipes in which a cooling medium or a heating medium may optionally be conveyed are passed through the carrier matrix, in order to cool the hydrogen reservoir during filling or to heat it during emptying.
U.S. Pat. No. 6,378,601 B1 discloses a process for filling a solid reservoir, in which hydrogen is used to cool the solid reservoir. The hydrogen flows through the solid reservoir by the flow-through method. Some of the hydrogen is absorbed by the storage material, while some of the hydrogen dissipates the heat generated in the process. The heated hydrogen is fed to a storage reservoir.
It is the object of the present invention to provide a solid reservoir for hydrogen which is as compact as possible, which has a variable layout and which is particularly suitable for use in a vehicle. It is also an object of the present invention to provide a process for filling such a hydrogen reservoir.